The invention relates to a quill for coordinate machines of an essentially rectangular, in particular squire cross-section, guided in bearing parts so as to be movable in a Z direction and accommodating a measuring feeler at its lower end.
Similar quills are disclosed in German No. OS 31 07 783 in the introductory description thereof. In order to reduce the weight of such quills it has been suggested in German No. OS 31 07 783 to depart from the square section of the quill and produce a quill of triangular section instead. In comparison with the square, and also in comparison with the generally known circular cylinder form, a triangular section presents less surface, whereby a corresponding weight reduction is achieved.
The new VDI acceptance guidelines for three coordinate measuring instruments provide a test for quills, allowing a maximum of two angular seconds for the twist angle or roll angle accuracy. This extraordinarily high accuracy is not attainable in the known quill designs with triangular or round section, or is attainable only at extremely high expense for assembly and adjustment. Maintaining the specified accuracy is problematical especially if, in large measuring machines, the quill is to be extended in the Z direction over a long distance of, say, two meters or more.